Monday, March 16, 2009
Leaping Atlantic Sturgeon
These are six foot long Atlantic sturgeon leaping in the Kennebec River in downtown Augusta, Maine as they get ready to mate and spawn. I filmed them in late June 2003 by sitting on the river bank aiming my movie camera and tripod at the river and letting it run for an hour at a time. Usually, the sturgeon would jump just upstream or downstream of the camera's field of view, meaning I got no shot. In order to get a good shot I had to have the zoom on the camera cranked to 10X, its highest setting. Unfortunately, using the 10X zoom greatly narrows the field of view, which means a sturgeon has to jump exactly in a 30-50 foot area to be filmed. By lowering the zoom, you get more sturgeon footage, but they are too far away to really show them off.
Nobody knows why Atlantic sturgeon jump. They only do it when they are getting ready to mate and spawn. My brother's theory is that leaping is a mating behavior, specifically, that it allows the sturgeon to locate each other, since the sound can be heard for long distances underwater, and it is obvious that the sturgeon try to make the loudest and biggest splashes possible when they jump. My hunch is that the males are doing it as a way to show off for the females, as in "my splash is the biggest and loudest." This theory is is difficult to test because you can't tell the males from the females when they jump. It could be tested if you caught about 20-30 sturgeon in a spawning area, identified their sex, visibly marked them according to their sex, and then watched to see who was doing the jumping: males, females or both.
Here's a really cool clip of an Atlantic sturgeon swimming along the bottom of Chesapeake Bay:
On the Kennebec River the Atlantic sturgeon appear in the Augusta area (40 miles above the ocean) in early June and stay until late July. Very little is known about them, except they became nearly extinct by the 1970s and are now slowly recovering in number. Their recovery has occurred for three reasons. First, the U.S. Clean Water Act has eliminated the severe water pollution that destroyed the Kennebec River for most of the 20th century. Second, in the early 1980s the State of Maine made it illegal for anyone to catch and keep a sturgeon. Third, in 1973, Richard Milhous Nixon signed the U.S. Endangered Species Act (ESA) into law, which protected the shortnosed sturgeon but not the Atlantic sturgeon. In 1998, Jasper Carlton of the Biodiversity Legal Foundation tried to rectify this omission by submitting a petition to list the Atlantic sturgeon as an endangered species under the U.S. Endangered Species Act. Mr. Carlton's petition was thorough and accurate. Mr. Carlton's petition was denied by the National Marine Fisheries Services because they believe Job One is to hasten and accelerate the death of all marine fish and mammals so we have big lifeless, empty oceans to dump nuclear waste in.